When an Old Enemy Aims to Be a New Coworker

By Caroline M.L. Potter, Yahoo! HotJobs

Moving on from a job can be tough when you've forged close bonds with your coworkers. But if you had a contentious relationship with a colleague, you may be glad to leave your old position -- and your nemesis -- in the dust.

But what happens when you see this ghost of workplaces past sitting in your current employer's waiting room, filling out a job application? Do you zip your lip? Or do you dish the dirt in an attempt to block the hire?

Assess the Situation

"It's a sticky situation," says career expert Cynthia Shapiro. "Your No. 1 job is to protect your job. If you are already at a company and you were there first, there's no reason you should sit by and let them hire your nemesis. If it's someone you simply just don't like, you may want to step back and consider your reservations carefully; but if it is truly your nemesis, take action. You don't want someone to jeopardize your job or your happiness."

Consider, too, whether this person reached out to you in an attempt to mend fences. "Everyone deserves a second chance," Shapiro says. "If this person did the whole mea culpa thing, you may want to forgive past mistakes. But if he's a horrible back- stabber who does get hired, it could erode the company's culture. And that's something you can't see on a resume."

Be Honest (Not Catty)

If you work for a small company, it's likely someone will connect the dots between the two of you and solicit your opinion. "When coworkers come to you and ask you about a potential employee, they want you to be honest," Shapiro says. "They're doing it because it is very difficult to really find out about someone and know if you're about to hire a bad seed."

When you do weigh in on a potential hire, don't make it personal. "You want to keep it as professional as possible," Shapiro says. "Be gracious and just say, 'I have to be honest -- this person wouldn't be my first pick.'" If you want to aid the process further, suggest other possible hires from colleagues with whom you did work well.

Know the Risk

If your employers fail to make the connection between you and your nemesis, should you offer an unsolicited opinion?

"You may want to just go in and test the waters [and] find out how it went," Shapiro says. If it looks like the hiring manager was impressed, Shapiro suggests you say something like, "I understand that he interviewed very well, and he's respected; but, confidentially, I'd like you to hire someone else."

The danger is that if you say something and this person is hired anyway, you may have tipped your hand, Shapiro says.

"It's a step you're taking to protect your job," she says. "You may feel horrible, but if this individual had behaved properly in the past, you wouldn't be doing this. Toxic behaviors are contagious and can change the entire atmosphere. You're doing your company a favor by revealing that someone isn't the best hire."